As in, power-efficient? I'd suggest a 7850 or a GTX 660, in that case. They're both pretty power-efficient and do decently well at the resolution you're looking for. a 7850 1GB can be found for around... $180 on average, a 2GB for roughly $20 more, and a GTX 660 for maybe $220 or so. However, for about $210, you can also get an XFX Double D Radeon 7870 as well. Any of those cards, and especially the GTX 660 and the Radeon 7870, will work at the resolution you've got very well.